fluentassert

Caution

Avoid using assertion libraries. Instead, use go-cmp and write custom test helpers. Using the popular testify may be also an acceptable choice, especially together with testifylint to avoid common mistakes. Use this library if you still want to. Consider yourself warned.

Description

Quick start

package test

import (
	"testing"

	"github.com/fluentassert/verify"
)

func Foo() (string, error) {
	return "wrong", nil
}

func TestFoo(t *testing.T) {
	got, err := Foo()

	verify.NoError(err).Require(t)           // Require(f) uses t.Fatal(f), stops execution if fails
	verify.String(got).Equal("ok").Assert(t) // Assert(f) uses t.Error(f), continues execution if fails
}

$ go test
--- FAIL: TestFoo (0.00s)
    basic_test.go:17:
        the objects are not equal
        got: "wrong"
        want: "ok"

Supported types

Deep equality

package test

import (
	"testing"

	"github.com/fluentassert/verify"
)

type A struct {
	Str   string
	Bool  bool
	Slice []int
}

func TestDeepEqual(t *testing.T) {
	got := A{Str: "wrong", Slice: []int{1, 4}}

	verify.Any(got).DeepEqual(
		A{Str: "string", Bool: true, Slice: []int{1, 2}},
	).Assert(t)
}

$ go test
--- FAIL: TestDeepEqual (0.00s)
    deepeq_test.go:20:
        mismatch (-want +got):
          test.A{
        -       Str:  "string",
        +       Str:  "wrong",
        -       Bool: true,
        +       Bool: false,
                Slice: []int{
                        1,
        -               2,
        +               4,
                },
          }

Collection assertions

package test

import (
	"testing"

	"github.com/fluentassert/verify"
)

func TestSlice(t *testing.T) {
	got := []int { 3, 1, 2 }

	verify.Slice(got).Equivalent([]int { 2, 3, 4 }).Assert(t)
}

$ go test
--- FAIL: TestSlice (0.00s)
    slice_test.go:12:
        not equivalent
        got: [3 1 2]
        want: [2 3 4]
        extra got: [1]
        extra want: [4]

Periodic polling

package test

import (
	"net/http"
	"testing"
	"time"

	"github.com/fluentassert/verify"
)

func TestPeriodic(t *testing.T) {
	verify.Eventually(10*time.Second, time.Second, func() verify.FailureMessage {
		client := http.Client{Timeout: time.Second}
		resp, err := client.Get("http://not-existing:1234")
		if err != nil {
			return verify.NoError(err)
		}
		return verify.Number(resp.StatusCode).Lesser(300)
	}).Assert(t)
}

$ go test
--- FAIL: TestPeriodic (10.00s)
    async_test.go:19:
        function never passed, last failure message:
        Get "http://not-existing:1234": context deadline exceeded (Client.Timeout exceeded while awaiting headers)

Custom predicates

package test

import (
	"strings"
	"testing"

	"github.com/fluentassert/verify"
)

func TestShould(t *testing.T) {
	got := "wrong"

	chars := "abc"
	verify.Any(got).Should(func(got string) bool {
		return strings.ContainsAny(got, chars)
	}).Assertf(t, "does not contain any of: %s", chars)
}

$ go test
--- FAIL: TestShould (0.00s)
    should_test.go:16: does not contain any of: abc
        object does not meet the predicate criteria
        got: "wrong"

Panics

Custom assertion function

package test

import (
	"testing"

	"github.com/fluentassert/verify"
)

type A struct {
	Str string
	Ok  bool
}

func TestCustom(t *testing.T) {
	got := A{Str: "something was wrong"}

	verifyA(got).Assert(t)
}

func verifyA(got A) verify.FailureMessage {
	return verify.And(
		verify.String(got.Str).Contain("ok").Prefix("got.String: "),
		verify.True(got.Ok).Prefix("got.Ok: "),
	)
}

$ go test
--- FAIL: TestCustom (0.00s)
    custom_test.go:17:
        got.String: the value does not contain the substring
        got: "something was wrong"
        substr: "ok"

        got.Ok: the value is false

Extensibility

Supported Go versions

Contributing

License